Piping systems in a variety of industrial settings are used to transport liquids and gases over a broad range of temperatures. In such piping systems, mixing of fluids of two different fluid streams may be necessary. In one example piping system, a first fluid at a first temperature in a first pipe may be continuously mixed with a second fluid at a second temperature in a second pipe to achieve a prescribed or desired mixing effectiveness. The temperature difference between the first fluid and the second fluid may be relatively large, and in some situations, mixing may actually be an injection of the first fluid in the first pipe into the second fluid in the second pipe. Because of the relatively large temperature differential that may exist between the first fluid and the second fluid, when such mixing or injecting occurs, a large temperature differential may be created within the pipe wall of the pipe receiving the injection of fluid. A relatively large temperature differential may result in unnecessary pipe repairs or replacements due to thermal stressing of the metal from which the pipe is constructed. To prevent the pipe wall of the pipe receiving the fluid injection from experiencing relatively large temperature fluctuations, improvement is needed. What is needed then is a device and method that permits maintaining a relatively small or no temperature differential along pipe wall sections in pipes that receive fluid injections at and near the location of the injections, without compromising mixing effectiveness of an injected fluid into a receiving fluid.